Shock-responsive latching device



Aug. 21, 1945. R B. IMMEL ET AL. 2,382,995

SHOCK RESPONSIVE LATCHING DEVICE Filed Nov. 24, 1945 2 Shets-Sheet 1[MUM/an WITNESSES: INVENTORS Z v 6040/? afmnve/ and 7 FFa k .f/amar. M'wBY v IZWKZ.

ATTORNEY tactors of the just-mentioned type.

Patented Aug. 21, 1945 UNITED 1 STATES PATENT OFFICE s'HocK-nEsroNsIvELATCHING DEVICE Ralph B. Immel, Wilkinsbur'g, Pa., and Frank Slamar,Annapolis, Md., assignors to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Application November 24,1943, Serial No. 511,564

3 Claims. (01. 74-527) No. $8,388, filed September 15, 1942, on a Latchfor contactors, the magnetic core structure of a relay-type contact-oris provided with a latch and has also a vibratory weight which ispivoted on and elastically braced against the core structure andoscillates upon the occurrence of shock thereby moving the latch intoengagement with the armature of the contactor to secure the armature inthe position which the armature assumed previous to the shock.

It is a general object of our invention to improve latchin devices andshock-protected con- More specifically, it is among the objects toincrease the efficacy and reliability of such devices, and also tofacilitate the manufacture and assembly of this type apparatus. We arealso aiming at providing a latching device which lends itself -morereadily than the known constructions to bein applied in relays, switchesandother apparatus of widely difierent design and purpose.

According to the invention, in one of its aspects, the latching deviceis arranged near the contacts of a contactor and particularly betweentwo spaced sets of contacts actuated by a rocking armature so that thelatch lies close to the path or periphery of contact motion. Thelatching device proper, including a movable latch member and a shock orvibration responsive oscillatory system, is provided with a'sup-port orframe structure separate from that of the apparatus to be protected soas to form a structurally and operatively separate unit.

These and other objects and features of the invention will be understoodfrom the following description of the embodiment of a shock-proofcontactor shown in the drawings.

Fig. lis a front view of the complete contactor; V

Fig. 2 is a side elevation of the same contactor;

Fig. 3 is a part-sectional side elevation, the sectional part extendingalong the plane indicated in Fig. 1 by the dash-and-dot" line marked IIIIII;

Fig. 4 shows thelatching device proper and mainly in a section throughthe symmetry axis of Fig. 1, the device being illustrated in conditioncorresponding to that shown in Fig. 3;

Fig. 5 represents the latching device by a sectional view similar tothat of Fig. 4, but with the latch moved into operative position;

Fig. 6 is a view of the latching device proper taken from the bottomside of Fig. 4, and

Fig. '7 is a view, similar to'Figs. 4 and 5, of a somewhat modified formof the latching device.

Referring to Figs. 1, 2, and 3, the illustrated contactor has a magneticstructure I which carries a magnet core 2 and a coil 3 placed around thecore. An abutment member 4 is mountedon the magnetic structure I and hasa portion 5 which extends towards the area in front of the magnet core.The abutment member 4 and the adjacent end of the structure I form acorner at 6 which serves a dihedral pivot bearing for the armature 1.The armature'is beveled so as to form a. knife-type edge which engagesthe pivot hearing. A weight 8 is firmly secured to the armature I, andso is a bracket 9 which forms an abutment for a coiled compressionspring whose other end is braced against an abutment formed by theportion 5 of the member 4. A locking member 20 is also rigidly securedto thearmature for a purpose to be described hereinafter.

Two contact members H are mounted on an insulating carrier ll secured tothe armature 'l and are each connected by a flexible cable [2 with tworespective terminals l3. Each contact I l cooperates with one of twostationary contacts M which are provided with terminalsl5 respectively.Blowout coils it serve to quench the interrupting arcs occurring betweeneach' pair of contacts II and Mduring the interrupting operation. nals15, the blowout coils i6, and the'terminals E3 of the movable'contact Hare mounted on a common base I! of molded insulating material which isfirmly secured to the magnetic structure I. The base I1 has a recess orgroove it in its center portion and a ridge !9 which traverses therecess in order to increase the mechanical strength of the molded body.I

The armature assembly, including the armature proper and the elements 9,20, I l and II attached thereto is so biased by the spring it that thepivot edge of the armature 'l is held against the dihedral pivot bearingat 6. In this manner, the armature assembly is constrained to performangular movements about the axis of the pivot bearing towards and awayfrom the magnet core. The force of spring I!) has also a component whicbiases the armature assembly away from the magnet core and towards astationary stop formed at? (Fig. 3) by the portion 5 of the abutment Thestationary contacts l4, their termi member 4. When the armature abutsagainst the stop, the movable contacts H are separated from thestationary contacts I4 (Fig. 2) so that the circuit between each pair ofterminals I3 and I5 is opened. When the relay coil,3 is energized, thearmature is attracted by the magnet core 2 and more: its smut "H intocircuit "closing position.

In order to prevent the above described contactor from performingundesired operations when subjected to shock and vibratiomespecially asoccurring on naval vessels due to the operation of their internalequipment or by contact with external objects, a latchinzdevice .isprovided. This latching device includes a substantially U-shaped supportor frame structure 2 |,consisting, for instance, of a sturdy metalcasting, whose base portion 22 is fastened by screws 22' to theinsulating base I1 and the magnetic structure I or the contactor (Fig.3).

Referring now to Elgs. 4, 5 and 6, 'a channelshaped latching lever 23has its flange portions 24 fulcrumed about a pin 26 which is riveted tothe two parallel legs of the U-shaped support 2| and located relativelyclose to the base portion 22 i of the structure. Another pin 21 rivetedto the legs of the support 2| at a place relatively remote from the baseportion 22has a projection'23 which serves as an abutment or holder fora wire spring 28. presses against the latching lever 23 so as to bias ittoward its inoperative position illustrated in Fllgs. 1, 3 and 4. Thelever 23 has an opening at for engagement with the latch 20 of thearmature 1 (Fig. 3) when the armature is in contact closing position.

A third pin 30 extending in parallel to pins '26 and 21 between the twolegs of the U-shaped support 2| and likewise fastened thereto byriveting, serves as a pivot for a weight 3| which has cams 32 and 33facing the latching lever 23. The cam 33 is part of a screw 34 whichpermits adjusting the cam as regards its distance from the main body ofthe weight 3|. A strand-shaped spring 33 is at one end firmly secured tothe weight 3| and has its other end extending through an opening in anextension 36 of the latching lever 23. The spring tends to hold theweight 3| in the position shown in Fig. 4, while permitting it toperform oscillatory motions about the pin 30 when subjected to shock orvibration. In other words, the Weight 3| and the spring 35 represent an05- cillatory mechanical system capable of damped vibrations.

When the contactor is exposed to shock or vi- L bration, the weight 3|will perform oscillatory motions previous to any appreciable motionperformed by the armature assembly of the relay due to the fact that themass and elasticity of the oscillatory latching system are dimensionedfor a considerably smaller time constant than the relatively heavy massand relatively stiff spring of the armature assembly. As soon as suchoscillations of the latching system occur, the weight 3| will move itscams 32 and 33 towards and away from the latching lever 23. When cam 33moves against the latching lever, it turns the lever against the forceof spring 28 into latching position. The cam 32 when moving against thelever 23 has the same effect. Consequently, both cams cooperate during asequence of Oscillations of weight 3| to render the latching leveroperative.

Fig. 5 represents a stage of vibratory operation in which theprojection33 has moved towards the lever 23. The same figure illustrates, by abroken This spring is wound around the pin 26 and line, a phase of thesame vibratory motion in which the cam 32 engages the lever 23. It willbe noted that the distance of projection 32 from the axis of oscillationis shorter than that of the cam 33. The difference is so dimensionedthat the torque imparted to lever 23 by either cam is approximatelyequal to that produced by the other cam.

Referring to the operation represented by Fig. 5, and assuming that therelay was in the inoperative position shown in Figs. 2 and 3 before theoccurrence of a shock, it will be apparent that, since the lever 23remains in the path of motion of latch 20 as long as the shock iseffective, the armature assembly cannot move towards the contact closingposition because the latch 20 would abut against the free end of thelatching lever 23,

as is illustrated in full line in Fig. 5.

Assuming now that the contactor was in circuit closing position beforethe occurrence of a shock, the operation of the latching lever 23 aselucidated by Fig. 5 will cause the opening 25 of the lever to pass overthe end of latch 20, as is shown in Fig. 5 by a dash line representationof the latch. Consequently, the contactor is now prevented fromperforming unintentional opening movements as long as the vibratoryfunction of the oscillatory system persists. In the modified embodimentshown in Fig. 7, the latching lever 24 and its opening 25' are shapeddifferently from the corresponding items of the above-describedembodiment, the pin 21 serving as a stop for limiting the motion of thelever towards the armature latch 20. Otherwise the design is similar tothat of the device previously described as will be apparent from thecorresponding reference numerals.

It is essential for the above described device that the latchingmechanism is located at the periphery of the armature close to thecontacts operated by the armature. In this location of the latchingdevice, a most eifective blocking of the armature and contact assemblyin either its opening or closing position is obtained. It is alsoimportant that the latching device has its own support and forms anoperative unit capable of operation independent of the contactor orother device to be protected, with the only exception that somelatch-like element 20 is to be provided at the apparatus to beprotected, such latch, however, being easily applicable or supplementedto almost any type of apparatus of interest. The provision of a separatelatching unit has the advantage that it may be added to differentcontactors and other apparatus to be protected from faulty operationunder shock or vibration. Such a separate latching unit offers thefurther advantage of facilitating the manufacture because it can becompleted and tested separate from the apparatus to be shock-proofed andpermits also an easy exchange of a latching unit in case of repairs.

Being aware of the fact that the apparatus and latching devices asdescribed in the foregoing may be modified in various respects withoutdeparting from the gist and scope of our invention, we wish thisdescription to be understood as illustrative and not in a limitingsense.

We claim as our invention:

1. A shock-responsive device for latching a contactor, comprising incombination a support; a latch lever having one end pivoted to saidsupport for limited angular motion and being normally biased towardinoperative position, a me-- chanical oscillatory device having anunbalance weight pivoted to said support to perform oscillatory pivotalmotion under shock, an adjusting screw passing through said weight so asto be engageable at one end with said lever and accessible at the sideof said weight away from said lever for adjusting the lever-engaging endrelative to said weight, a cam member disposed on said weight at aplaceradially opposite to said screw with respect to the pivot axis ofsaid weight and arranged for engaging said lever so that said screw andsaid cam member move said lever alternately into latching positionduring the occurrence of shock.

2. A shock-responsive device for latching a con' tactor, comprising incombination a support having a base portion and two leg portionsextending substantially at right angles to said base portion, a pivotdisposed between said legs near said base portion, a spring biasedlatching lever fulcrumed on said pivot and extending away from said baseportion between said leg portions, another pivot disposed between saidleg portions away from said base portion, a mechanical vibra' torysystem having a weight mounted on said other pivot and two cam membersdisposed on said weight at opposite sides of said other pivot andprojecting toward said lever for alternately moving said latching leveragainst its bias into latching position upon the occurrence ofoscillatory pivotal motion of said w'eight due to shock, one of said cammembers being adjustable relative .to said weight.

3. A shock-responsive latching device, comprising in combination asubstantially U-shaped support having a base portion designed forattachment to an apparatus to be latched and two leg portions extendingin parallel to each other, a pin secured between said leg portions nearand in parallel to said base, a spring biased latching lever pivoted onsaid pin and extending away from said base, another pin secured betweensaid leg portions away from said base portion, and a mechanicalvibratory system having a weight mounted on said other pin, and two cammembers disposed on said weight at opposite sides of said other pin anddirected toward said lever for alternately moving said lever against itsbias into latching position upon the occurrence of oscillatory pivotalmotion of said weight due to shock, one of said cam members. having anadjusting screw for adjusting its position relative to said weight.

RALPH B. IMMEL. FRANK SLAMAR.

